What is ERCOT and Why Does It Matter?

ERCOT runs the electricity grid that covers about 90% of Texas. If you live in the deregulated market — Dallas, Houston, Fort Worth, most of the I-35 corridor — your power flows through their system.

Most Texans go their whole lives without thinking about ERCOT. Until Winter Storm Uri.

This is the explainer for the people who pay the bills.

ERCOT in one sentence

The Electric Reliability Council of Texas is a non-profit that balances electricity supply and demand across the Texas grid, second by second, every day of the year.

That's it. They don't own power plants. They don't own wires. They don't sell electricity to you. They're a referee — making sure enough generation is online to meet demand, dispatching plants up and down in real time, and operating the wholesale market where electricity is bought and sold.

When ERCOT does its job well, you don't notice it. The lights stay on. The market clears. Bills arrive about as expected.

When ERCOT fails — and they have, most catastrophically in February 2021 — you notice immediately.

Why Texas has its own grid

The U.S. has three big electrical grids: the Eastern Interconnection, the Western Interconnection, and the Texas Interconnection (ERCOT). Texas runs separately, on purpose.

The story goes back to the 1930s. The federal government passed laws giving itself regulatory authority over electricity that crossed state lines. Texas utilities, not wanting federal oversight, agreed to keep their grid contained inside Texas borders. The result: a state grid that doesn't physically connect (much) to the rest of the U.S.

Today there are a handful of small DC interconnects to Mexico, the Eastern Interconnection, and the SPP region — enough to move a few hundred megawatts. But for practical purposes, ERCOT is an island. If demand spikes inside Texas and supply doesn't keep up, Texas can't just import power from Louisiana. The grid stands or falls on its own.

That isolation is the entire reason Winter Storm Uri became a disaster instead of an inconvenience.

How wholesale prices end up on your bill

The market ERCOT runs is wholesale. Power plants offer to sell electricity at a price; large buyers (mostly utilities and REPs) bid to buy. ERCOT clears the market every five minutes, setting a "real-time" price for each location.

That wholesale price is the input cost to every Retail Electric Provider in Texas. When wholesale prices are low (mild weather, abundant wind generation), REPs can offer cheap fixed-rate plans. When wholesale prices are high (heat wave, generation outage, freeze), REPs that hedged well stay solvent; REPs that didn't get crushed.

Most Texas residential customers are on fixed-rate plans, which means the REP absorbs the wholesale risk. Your bill stays the same whether wholesale is 3¢/kWh or 300¢/kWh — for the duration of your contract.

But: that protection is real until you let your contract roll to month-to-month. Then you're exposed.

What actually happened during Winter Storm Uri

February 14-19, 2021. Severe cold weather across Texas. About 4.5 million homes lost power. ERCOT initiated rolling blackouts. Some areas were dark for days.

The market-side problem was the wholesale price. ERCOT's pricing cap at the time was $9,000 per megawatt-hour — $9 per kWh, roughly 80× a normal residential rate. For four straight days, prices ran at or near that cap.

Most retail customers were insulated. Their fixed-rate plans charged what the contract said. The REP took the loss.

A small number of customers — those on variable-rate or "indexed" plans that passed wholesale prices straight through — saw bills of $5,000, $10,000, even $17,000 for a single week.

The customer wasn't wrong. The product wasn't designed for that scenario, and the REP was within its contractual rights to charge it.

After Uri, the Texas Legislature passed Senate Bill 3, which restricted some of the most-exposed retail products. The PUCT changed ERCOT's pricing rules. But the underlying structure — ERCOT as a market operator, retail customers on contracts that vary in how much risk they absorb — is still in place.

Who does what — three different bodies, three different jobs

This is where Texas confuses people. Three entities touch your electricity service, and they're not the same:

ERCOT — operates the grid. Balances supply and demand. Doesn't write rules. Doesn't sell electricity. Doesn't bill you.

The Public Utility Commission of Texas (PUCT) — the regulator. Writes the rules ERCOT and retail providers follow. Sets TDU delivery rates. Disciplines providers that violate rules. Doesn't operate anything.

Your Retail Electric Provider (REP) — the company on your bill. Sells you the plan. Buys electricity wholesale from ERCOT's market. Manages your account. Hires customer service.

If you have a billing dispute, that's your REP. If your power's out, that's your TDU (Oncor, CenterPoint, AEP, or TNMP). If you think a market rule is unfair, that's the PUCT. ERCOT itself almost never talks to residential customers directly.

Why ERCOT matters even when it's working

Even in a normal year, ERCOT's decisions shape your bill in ways you don't see directly:

• The reserve margin they target (currently around 13.75%) determines how tight supply runs during peak hours. Tighter margins mean more wholesale price volatility.
• Capacity markets — or the lack of them, in Texas — affect how power plants get paid to stay available. Texas runs an energy-only market, which means plants only get paid when they generate. Other states pay plants to be on standby. The Texas model is cheaper in normal years and riskier during extreme weather.
• Interconnection queues determine how fast new generation comes online. Texas leads the nation in wind and solar interconnections; ERCOT processes those queues.

None of this shows up on your monthly bill as a line item. But it shapes the wholesale prices your REP buys at, which determines what plans they can offer you for the next year.

What ERCOT can't tell you

ERCOT publishes a lot. Real-time prices. Reserve margins. Generation mix. Outage maps. All of it is public.

What ERCOT can't tell you: which plan is right for your home. They don't operate the retail market. They don't know your usage. They don't compare REPs. If you're trying to make a plan-shopping decision, ERCOT's public data is interesting context — but it's not actionable for you directly.

That's what the PUCT's complaint scorecard, your REPs' EFLs, and a comparison site are for.

The honest close

ERCOT exists because Texas wanted to keep electricity regulation in Texas. The trade-off is an isolated grid that can't easily borrow power from neighbors when things go wrong. Most years that doesn't matter. The years it does, it really does.

The grid you depend on is one of the most-watched, most-studied utility systems in the country. Whether it's reliable enough for the future Texas wants is a real question. But for shopping-an-electricity-plan purposes, you don't need to be an ERCOT expert.

You need to know it exists, know your fixed-rate plan insulates you from its wholesale prices, and know which body to call when something specific goes wrong.

That's enough.

» MORE: The Texas power grid · Texas deregulation explained